Speaker
Dr
Naoko Ashikawa
(National Institute for Fusion Science)
Description
Generation and accumulation of metal dust particles are important issues in material migration of the Plasma Facing Components (PFCs) such as tungsten (W) and Beryllium (Be) from viewpoints of the plasma operation, maintenance and safety in accidents for ITER and Demo. On the other hand, analysis results of the material components and the internal structure of the dust particle are few because plasma experiment devices are limited and analysis procedures/devices are not well established. Analysis results of, in particular, Be dust particles are important for ITER, which have not been reported.
A comprehensive analysis of collected dust and divertor tiles in the Joint European Torus (JET) ITER-like Wall (ILW) after the first campaign in 2011-2012[1] has been carried out at the International Fusion Energy Research Centre (IFERC) in order to identify dust characteristics such as structures, material components and hydrogen isotope retention. After the first campaign of the JET-ILW operation in 2011-2012, dust particles were collected from 92% of the divertor surface area. Totally about 1 gram was collected: 0.7 g and 0.3 g from the inner and outer divertors, respectively [1]. The analysis started from a large-size dust flake, i.e. 40-120 micron, to determine material components both on the surface and in the cross-section by cutting the dust particle using a focused ion beam. For the flake-type Be-base dust particle, it was found that the damaged Be crystal structure contained a larger oxygen component near the surface (~2 micron) measured by transmission electron microscopy and electron probe micro analyser, respectively. Deuterium (D) retention in small weight of dust particles (4.4 mg) was evaluated to be 1.2 x 10^21 atoms/g by thermal desorption spectrometry, which corresponds to 8.2 x 10^20 atoms for all dust particles collected from the inner divertor (0.7 g). This result firstly suggests that contribution of dust particles to the total retention in experiment is small, i.e. less than 1% of the total retention in deposition layers of the inner divertor target.
In this paper, a detailed characterization, which is a relationship between retained hydrogen isotopes and compositions of JET-ILW dust particles, will be presented.
[1] A. Widdowson, et al., Phys. Scr. T159 (2014) 014010.
| Country or International Organization | Japan |
|---|---|
| Paper Number | EX/P6-19 |
Primary author
Dr
Naoko Ashikawa
(National Institute for Fusion Science)
Co-authors
Dr
Aleksandra Baron-Wiechec
(UKAEA)
Dr
Anna Widdowson
(UKAEA)
Dr
Dai Hamaguchi
(Japan Atomic Energy Agency)
Mr
Hironiri Kurotaki
(Japan Atomic Energy Agency)
Dr
Hiroyasu Tanigawa
(Japan Atomic Energy Agency)
Dr
Jae-Hwan Kim
(Japan Atomic Energy Agency)
Dr
Justyna Grzonka
(Warsaw University of Technology)
Dr
Kalle Heinola
(University of Helsinki)
Dr
Kanetsugu Isobe
(Japan Atomic Energy Agency)
Dr
Makoto Oyaidzu
(Tritium Technology Gr., Fusion Research Development Directorate, Japan Atomic Energy Agency)
Dr
Marek Rubel
(KTH, Royal Institute of Technology)
Dr
Masanori Hara
(University of Toyama)
Dr
Masaru Nakamichi
(Japan Atomic energy Agency)
Dr
Masayuki TOKITANI
(National Institute for Fusion Science)
Dr
Mitsutaka Miyamoto
(Shimane University)
Dr
Nobuyuki Asakura
(Japan Atomic Energy Agency)
Dr
Suguru Masuzaki
(National Institute for Fusion Science)
Dr
Suguru Nakano
(Japan Atomic Energy Agency)
Dr
Teppei Otsuka
(Kyushu university)
Prof.
Yuji Hatano
(Hydrogen Isotope Research Center, University of Toyama)
Dr
Yuji Torikai
(University of Toyama)
Dr
toshihiko yamanishi
(Japan Energy Atomic Agency)
